by Oren Dorell, USA TODAY

by Oren Dorell, USA TODAY

Secretary of State John Kerry is traveling to Geneva to join negotiations on Iran's nuclear program, his spokeswoman said Friday afternoon.

"Secretary Kerry will travel to Geneva later today with the goal of continuing to help narrow the differences and move closer to an agreement," State Department spokeswoman Jen Psaki said in a statement.

Kerry decided to go after consulting with European Union representative Catherine Ashton and his negotiating team in Geneva, Psaki said.

U.S. negotiators and their counterparts from the United Kingdom, France, Germany, Russia and China have been meeting with the Iranians since Wednesday in an effort to strike an interim deal to delay Iran's nuclear program while a larger deal is worked out that would prevent the Islamic Republic from obtaining nuclear weapons.

Russian foreign minister Sergei Lavrov is already there.

The current talks, which are in their third round, aim to take what Kerry has called "a first step" that would delay Iran's progress toward the ability to produce nuclear weapons for six months while a more comprehensive agreement is worked out.

The last round of talks broke down over French concerns about the status of Iran's heavy water power plant under construction in Arak, and over Iran's demand that any agreement recognize the production of nuclear fuel as Iran's sovereign right. The USA does not recognize such a right.

World powers have imposed crippling economic sanctions on Iran to convince it to suspend production of nuclear fuel in accordance with United Nations Security Council resolutions, and to prove its nuclear program is peaceful in compliance with the Non-Proliferation Treaty, which Iran has signed.

Iran, which seeks to have the sanctions lifted, says its nuclear program has peaceful aims. But the U.N.'s nuclear watchdog, the International Atomic Energy Agency, has reported over the years multiple discoveries of secret Iranian nuclear sites, work on nuclear detonators and implosion devices with assistance from foreign scientists, documents describing safety arrangements for a nuclear test, and plans for a spherical payload for Iranian missile.

The United States, Israel and European countries have said they suspect Iran of developing a nuclear weapons program. President Obama has said the USA will prevent Iran from obtaining a nuclear weapon and Israel has threatened to use military force to prevent what it considers an existential threat.